Looper thread controlling mechanism for sewing machines



June 6, 1944. E K 2,350,965

LOOPER THREAD CONTROLLING MECHANISM FOR SEWING MACHINES Filed April 30, 1943 3 Sheets-Sheet l guvewilkov E. MUECKE June 6, 1944.

LOOPER THREAD CONTROLLING MECHANISM FOR SEWING MACHINES 3 Sheets-Sheet 2 Filed April 30, 1943 Patented June 6, 1944 UNITED STATES PATENT OFFICE LOOPER THREAD CONTROLLING MECHA- NISM FOR SEWING MACHINES Application April 30, 1943, Serial No. 485,148

8 Claims.

This invention relates to sewing machine thread-controllers and more particularly of the type to control the looper-thread of a chainstitch sewing machine.

An object of the present invention is to provide a looper-thread control for a machine of this type whereby thread for the looper is pulled from the supply commensurate with the length of stitch.

- With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangement of parts hereinafter set forth and illustrated in the-accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

In the accompanying drawings, Fig. 1 is a front sectional elevation of a sewing machine embodying my improvement. Fig. 2 is a top plan view of a portion of the sewing machine bed. Fig. 3 is an end elevation of the sewing machine head, partly in section. Fig. 4 is a detailed view of a portion of the thread-laying mechanism.

'Fig. 5 is a sectional elevation on line AA of Fig. 2 of the looper thread take-up, nipper and pull-off mechanisms. Fig. 6 is a sectional elevation, on lines 13-3 of Fig. 2, of the'feed actuating eccentric with its pull-off arm, thread-stripper and thread-guides cooperating therewith. Fig. 7 is a detail of the feed adjusting slide-block with pull-01f finger. Fig. 8 is a detailed view, partly in section, of the looper-thread take-up and Fig. 9 is a detailed view, partly in section, of a portion of the mechanism for actuating the covering thread-laying device.

The invention is disclosed as embodied in a double-thread chain-stitch sewing machine having the usual bed I and bracket-arm 2 with overhanging head 3. Journaled in the bed I is the rotary main-shaft 4 with a belt-wheel 5 secured at its free end. The'main-shaft 4 is also provided with spaced crank-disks 6 connected by a. crank-pin 'lembracedby the lower end of a pitman 8 whose upper end is journaled upon a pin 9 extending from the crank-arm Ill fixed .upon the upper rock-shaft ll suitably journaled in the bracket-arm 2. The free end of the rock- -shaft is provided with a crank-arm l2 with a pin [3 having a link connection l4 with a pin l5 of a block l6 clamped upon the needle-bar I1 carrying atzitslower endthe spaced needles [8. The looper-actuating mechanism embodied -in this machine isshown anddescribed in my by stitches.

The feeding mechanism, of the usual four' mo- 1 pending application, Serial No. 476,831, filed February 23, 1943.

It comprises an oscillating looper l9 supported by a carrier secured at its lower end upon a shaft 2| journaled in the sewing machine bed, crosswise of the main-shaft. The looper receives its endwise or loop-seizing movements from an eccentric 22, fixed upon the main-shaft 4, and embraced by the strap-end of a short pitman 23 whose other end engages a ball stud 24 formed upon the end of a crank-arm 25 clamped upon the cross-shaft 2|.

To impart sidewise movements to the looper, the carrier 20 is provided with an 'arcuately shaped clearance slot 26 entered by a slide-rod 21 provided with spaced collars 28 embracing the looper-carrier 20. The free end of the slide-rod 21 is provided with spaced cars 29 between which is mounted, on a pivot-pin 30, a lug 3| extending from a sleeve 32 embracing an eccentric 33 secured upon the main-shaft 4.

The sewing machine is further provided with a thread-laying mechanism comprising a spreader and thread-carrying implement for depositing, in advance of the needles, a covering thread upon the upper face of the work. In orderto operate these parts the needle-bar actuating crank-arm l2 has pivotally mounted thereon 'a vertically disposed hollow sleeve 34 entered-by a rod 35 extending upwardly from a collar --36 clamped upon a horizontally disposed sliderod 31 entering a suitable bearing aperture in the head 3 of the bracket-arm 2. Depending from the collar 36 is a slide-block 38 embraced by the forked arm 39 secured upon a. vertically disposed hollow bushing 40 suitably journaled in the head 3, embracing and forming a bearing for the presser-bar 4|, carrying at its lower end the usual presser-foot 42 retained in work-engaging position by the flat spring 43. Clamped upon the lower free end of the hollow bushing 40 is a laterally extending arm 44 supporting the spreader 45. Also clamped upon the lower free-end of the bushing 40 is a second arm 46 to the free end of which is pivotally secured a slide-block 41 entering a slotted rocker arm 48 pivotally mounted at 49 upon a bracket 50 depending from the head 3. Depending from arm 48 is a downwardly extending thread-carrying implement 5|. During the stitching operation the spreader 46 and thread-carrying implement '5l deposit a covering thread in a sinuous path upon the upper face of the work and secure it thereon tion type, comprises the feed-dog 52 clamped upon'the feed-bar 53 by the fastening screw 54. The feed-bar receives its rising and falling movements from the eccentric 55 mounted upon the shaft 4. The rear end of the feed-bar 53 is mounted upon a rocker 56 journaled upon the short shaft 'Lsupp0rted by the sewing machine bed I, in the rear of. the main-shaft 4. Journalled upon the bearing stud 58 entering the feed-rocker 56 is one end of a pitman 59 whose other end embraces the adjustable feed-actuating ball eccentric 60 mounted upon the slideblock 6| disposed in the lateral transverse slideway in the collar 62 fixed upon the main-shaft 4. The feed-cam or operating eccentric, 60 is formed with an elongated clearance slot 63 embracing the main-shaft and the slide-block 6| has upon its rear face lugs 64 entering the annular grooves 65 in the head of an adjusting screw 66 fitted in a suitably threaded transverse aperture in the collar 62. Turning of the screw 66 serves to move its head within the countersin-k formed in the collar 62 and to thereby similarly shift the block 6| to vary the eccentricity of, the camor eccentric 60 carried thereby, resulting in a change in the stitch length.

Recessed in the block BI and secured thereto by a fastening screw 61 is a looper thread pulloff or thread-engaging member 68 slotted at its tree end to embrace a thread stripper-finger 69 secured upon thecarrier-plate ill by fastening screws H. The carrier-plate 10 is secured upon a bracket. 85 by fastening screws 86 and the bracketis secured by a screw 81 upon the upwardly extending pedestal 88 of the sewing machine bed 1., The stripper-finger 69 is provided with; a thread-receiving slot 12 upwardly inclined at one end in the path of the pull-01f finger 68. The upwardly inclined. end. of the thread-slot insures an early cast-off or disengagement of the thread from the pull-off member when the sewing machine main-shaft 4 is accidentally turned in thewrong. direction (clockwise) thereby eliminating thedanger of; winding of the looperthread around.- the feed-actuating eccentric. Secured by rivetingor otherwise upon the under face of the carrier-plate 1D, and projecting upwardly through suitable apertures 13, are two thread-guiding eyes 14 disposed upon opposite sides ofnth e pull-off finger 68 and stripper 69.

Also mounted upon the carrier plate 16 is: a

.looper thread-nipper comprising the opposed spring members and lfi/ secured upon the carrier plate by a fastening screw 1'1. Projecting through a suitable aperture in the carrier plate in is a nipper actuating cam 18 secured upon the main-shaft, 4.

mounted upon the shaft 4, and projecting upwardly: through a suitable slot .inthe carrier plate m. Spaced above and secured to the carrier plate. by aclamp-screw 80 is the thread-detainer 6| the form of a U shaped wire loop embracmg the thread: take-up cam 19. Adjustably secured by screws 82 uponthe,carrier-plate'lfl, and at. opposite sides of the-thread-cam '19, are the thread-guides 83. each of which is in the formof a5 hookhaving a forwardly openingthreadreceiving throat leading to the bottom or reverse bendwhich; guides-the looper-thread, as more fully described in the Clayton patent above reterredto;

thread-eye 14 on the carrier-plate ID, thence through the slot 12 in the stripper-finger 69, thence through the thread-eye" on the other side of the finger 69. From here the looperthread is passed between the nipper springs 15 and 15 into the throat of the first thread-receiving hook 83 thence beneath the thread-detainer 8| into the throat of the second thread-receiving hook 83 and thence into the eye of the looper l9.

During the stitching operation of the sewing machine, the looper thread is controlled as follows: When the looper l9 moves forward in entering and seizing the needle-thread loops, the nipper springs l5, 16 are separated, with no drag on the thread. This permits free movement of the thread, as required by the looper, from a bight of thread previously drawnfrom the source of supply by the pull-ofi finger or thread-engaging member 68. During the backward movement of the looper, the nipper springs 1516 are closed upon the thread, and the slack thread from the looper is taken up by the rotation of the take up cam 19. During this time the pull-ofi finger 68 engages the thread and pulls off from the supply the required length of looper thread for incorpc-ration in the next stitch.

In order to change the length of stitch. the adjusting screw 66 is turned. toshift the block 6l and vary the eccentricity of the cam ;60.-- Such adjustment will also concomitantly change the effective path of movement of the thread pulloff finger- 68 carriedby the block H with respect to the stripper finger 69, increasingonly by the necessary length the looper thread required for the succeeding stitch pulledofi from thesupply when the length'of stitchis' increaseda-nd vice versa. I

It will be readily understood that the screw 66 constitutes a common element or interen'gaging connection between the block 6|" and finger 66 for increasing the length of stitch and the length of looper-thread pulled off.

It will be observed that the sewing machine disclosed in the annexed drawings is provided with two rotary looper thread-controllers one disposed upon either side of thenipper, whereby, when the nipper springs 15 and; I6 are closed upon the looper-thread, the controller I9 takesup the slack in the looper-threadduri-ng the retractive movement of the latter. while the other threadcontroller 68 draws only sufiicien-t thread from the supply for the succeeding stitch.

Having thus set forth the nature of the invention, what I claim herein is:

1. The combination with stitch-forming mechanism including an oscillating thread-carrying looper, of a nipper for the looper-thread. astrinper having a, thread-receiving slot, thread-guides disposed upon either side of said. stripper, and a rotary thread. pull-off cooperating withsaid stripper and thread-guides for drawing'loope'fithread from the suppl 2. The combination with stitch-forming mechanism includingv an oscillating thread-carrying looper of a nipper forthe: looper-tln'ead, a.stripper having athread-receiving slot inclined up- Wardly at one. end; thread-guides disposed. at either side of said stripper and apull ofi coupesating with said stripper and thread-guides adapted for drawing thread from the supply when rotated in one direction and said stripper disengaging said thread from the pull-oil when it is rotated in the opposite direction.

3. The combination with a sewing machine including a reciprocating needle, an oscillating thread carrying looper and a feeding mechanism, an adjustable feed-operating eccentric, of a looper thread pull-off device mounted upon said eccentrio and including a rotary thread-engaging member governed in its path of movement by adjustment of said eccentric.

4. In a sewing machine, a rotary shaft, a collar on said shaft, an eccentric adjustably mounted on said collar, a thread-engaging member sustained by said collar and associated with said eccentric for adjustment with the latter, and stationary thread-guides cooperatively related to said thread-engaging member.

5. In a sewing machine, the combination with an adjustable feed-actuating eccentric including a, collar provided with a transverse slideway, a block fitted in said slideway, an eccentric carried by said block, means for shifting the block and collar relatively and a thread-engaging member carried by said block.

6. The combination with a feeding mechanism of a sewing machine including a, feed-dog, an eccentric for imparting work-advancing movement to said feed-dog, a looper thread nipper, spaced thread-guides for the looper-thread, a threadstripper, an arm carried by said eccentric and cooperating with said thread-stripper and threadguides for pulling ofi looper-thread and means for adjusting the throw of said eccentric for concomitantly varying the amplitude of the workadvancing movements of the feed-dog and the length of looper-thread pulled from the supply.

7. The combination with a feeding mechanism of a sewing machine comprising a feed-dog, means for imparting to said feed-dog rising and falling movements, an eccentric for imparting work-advancing movements to said feed-dog, a looper thread nipper, thread-guides for the looper-thread, a thread-stripper, a slide-block mounted in said eccentric, an arm carried by said slide-block and arranged to cooperate with said thread-guides and stripper to pull off thread from the supply, and a common element for concomitantly varying the amplitude of the workadvancing movements Of the feed-dog and the length of looper-thread pulled oil from the supply.

8. The combination with a feeding mechanism of a sewing machine including a feed-dog, an eccentric for imparting work-advancing movements to the feed-dog having a guide-way, a looper thread nipper, thread-guides and a thread-stripper for the looper-thread, a block adapted for sliding movements in the guide-way of the eccentrio, a thread pull-01f arm for the looper thread carried by said block, and an adjusting screw forming an interengaging connection between said block and eccentric for concomitantly varying the amplitude of movement of the feed-dog and the pull-off action of the arm,

EDWARD MUECKE. 

